docs: def _decompress_nist256(pubkey):
      """
      Load public key from the serialized blob.
  
      The leading byte least-significant bit is used to decide how to recreate
      the y-coordinate from the specified x-coordinate. See bitcoin/main.py#L198
      (from https://github.com/vbuterin/pybitcointools/) for details.
      """
      if pubkey[:1] in {b'\x02', b'\x03'}:  # set by ecdsa_get_public_key33()
          curve = ecdsa.NIST256p
          P = curve.curve.p()
          A = curve.curve.a()
          B = curve.curve.b()
          x = util.bytes2num(pubkey[1:33])
          beta = pow(int(x * x * x + A * x + B), int((P + 1) // 4), int(P))
  
          p0 = util.bytes2num(pubkey[:1])
          y = (P - beta) if ((beta + p0) % 2) else beta
  
          point = ecdsa.ellipticcurve.Point(curve.curve, x, y)
          return ecdsa.VerifyingKey.from_public_point(point, curve=curve,
                                                      hashfunc=hashfunc)
      else:
          return None